public static StylusPointCollection GetArrowCorner(StylusPointCollection collection, double ratio = 5)
{
try
{
StylusPointCollection corners = GetTriangleCorner(collection);
if (corners != null && corners.Count == 4)
{
StylusPoint first = collection[0];
StylusPoint end = collection[collection.Count - 1];
StylusPoint firstCorner = corners[0];
StylusPoint endCorner = corners[1];
double minFistDis = double.MaxValue;
double minEndDis = double.MaxValue;
foreach (StylusPoint point in corners)
{
double dis = MathMethods.GetPowDistanceBetTowPoints(point.X, point.Y, first.X, first.Y);
double endDis = MathMethods.GetPowDistanceBetTowPoints(point.X, point.Y, end.X, end.Y);
if (minFistDis > dis)
{
minFistDis = dis;
firstCorner = point;
}
if (minEndDis > endDis)
{
minEndDis = endDis;
endCorner = point;
}
}
StylusPoint centerCorner = corners.FirstOrDefault(item => item != firstCorner && item != endCorner);
if (centerCorner != null && centerCorner.X > 0 && centerCorner.Y > 0)
{
double cf = MathMethods.GetDistanceBetTowPoints(centerCorner.X, centerCorner.Y, firstCorner.X, firstCorner.Y);
double ce = MathMethods.GetDistanceBetTowPoints(centerCorner.X, centerCorner.Y, endCorner.X, endCorner.Y);
double cf_ce = Math.Abs(cf - ce);
if (cf_ce > 150)
{
return(null);
}
double fe = MathMethods.GetDistanceBetTowPoints(firstCorner.X, firstCorner.Y, endCorner.X, endCorner.Y);
// cosA = (c^2 + b^2 - a^2) / (2·b·c)
double cosA = (cf * cf + ce * ce - fe * fe) / (2 * cf * ce);
if (cosA < 0.04 || cosA > 0.93)
{
return(null);
}
#region Check bound is two line
//Get line one function
double line1K = (centerCorner.Y - firstCorner.Y) / (centerCorner.X - firstCorner.X);
double line1A = line1K;
double line1B = -1;
double line1C = centerCorner.Y - line1K * centerCorner.X;
//Get line two function
double line2K = (centerCorner.Y - endCorner.Y) / (centerCorner.X - endCorner.X);
double line2A = line2K;
double line2B = -1;
double line2C = centerCorner.Y - line2K * centerCorner.X;
int line1Count = 0;
int line2Count = 0;
double lineDis1 = MathMethods.GetDistanceBetTowPoints(centerCorner.X, centerCorner.Y, firstCorner.X, firstCorner.Y);
double lineDis2 = MathMethods.GetDistanceBetTowPoints(centerCorner.X, centerCorner.Y, endCorner.X, endCorner.Y);
double line1offset = lineDis1 * ratio / 100;
double line2offset = lineDis2 * ratio / 100;
for (int i = 0; i < collection.Count; i++)
{
double dis1 = MathMethods.GetDistanceBetPointToLine(collection[i].X, collection[i].Y, line1A, line1B, line1C);
if (dis1 < line1offset)
{
line1Count++;
}
else
{
double dis2 = MathMethods.GetDistanceBetPointToLine(collection[i].X, collection[i].Y, line2A, line2B, line2C);
if (dis2 < line2offset)
{
line2Count++;
}
}
}
if (collection.Count - (line1Count + line2Count) > collection.Count / 20)
{
return(null);
}
#endregion
StylusPoint maxDisPoint = firstCorner;
StylusPoint minDisPoint = endCorner;
double maxDisCenter = cf;
double minDisCenter = ce;
if (cf < ce)
{
maxDisPoint = endCorner;
minDisPoint = firstCorner;
maxDisCenter = ce;
minDisCenter = cf;
}
//line:y=a+bx;
double b = (maxDisPoint.Y - centerCorner.Y) / (maxDisPoint.X - centerCorner.X); //(y1-y2)/(x1-x2)
double a = 0 - b * centerCorner.X + centerCorner.Y; //-b*x1+y2
double startTest = Math.Min(maxDisPoint.X, centerCorner.X);
double endTest = Math.Max(maxDisPoint.X, centerCorner.X);
Point targetPoint = new Point(maxDisPoint.X, maxDisPoint.Y);
for (double i = startTest; i < endTest; i += 1)
{
double y = a + b * i;
double dis = MathMethods.GetDistanceBetTowPoints(i, y, centerCorner.X, centerCorner.Y);
if (Math.Abs(minDisCenter - dis) <= 5)
{
targetPoint.X = i;
targetPoint.Y = y;
break;
}
}
if (targetPoint.X <= 0 || centerCorner.X <= 0)
{
#if DEBUG
throw new Exception("targetPoint.X should noe be zero");
#endif
}
StylusPointCollection result = new StylusPointCollection();
result.Add(new StylusPoint(targetPoint.X, targetPoint.Y, 0.5f));
result.Add(centerCorner);
result.Add(minDisPoint);
return(result);
}
}
}
catch (Exception ex)
{
Trace.WriteLine(ex.StackTrace);
#if DEBUG
throw ex;
#endif
}
return(null);
}